<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        function f() {
            var start = 13;
            var total = 0;
            return {
                price: function (n) {
                    if (n<3){
                        total = start;
                    }else {
                        total = start + (n-3)*5;
                    }
                    return total;
                },
                yd: function (flag) {
                    return flag ? total + 10:total;
                }
            }
        }
        console.log(f().price(5));
        console.log(f().yd(true));
    </script>
</head>
<body>

</body>
</html>